It was a tough nut to crack, and the discovery is the result of twenty years of curiosity.

The nerve network in squid skin is immensely complex, and now the ability to manipulate that system offers new opportunities for active camouflage.

DARPA has a number of programs that set out to hack biology. This is one of them, seeking to exploit the squid's advanced camouflage for military use.

The colors come from "iridiphores" on the squid's skin. Now that the scientists know which nerves stimulate which iridiphores — not to mention how to electrically shock the nerve to project the right color — they'll be able to advance the research on iridiphore manipulation.